HMS Porpoise (N14): From Laying Mines to Ferrying Commandos in the Pacific

The Build: Barrow

HMS Porpoise was built by Vickers-Armstrongs at Barrow, launched on 30 August 1932 and commissioned on 11 March 1933, a Grampus-class submarine purpose-built for minelaying, capable of carrying fifty mines in place of a conventional torpedo loadout, a specialised and properly demanding role that required precise, dangerous work close to enemy waters.

Fifty mines instead of torpedoes is not a modification. It is a different way of fighting. A submarine with torpedoes has to find a target, get into a firing position and be there at the right moment, and if the target does not come she achieves nothing. A minelayer does not need to meet anybody. She goes to a place her enemy has to use, a harbour approach or a swept channel or a strait, lays her mines from a set of rails running down the length of the casing, and leaves. What she has planted then works for months without her.

The catch is where the work has to be done. Mines are only useful in shallow water close to the coast, which is exactly where a submarine is most easily seen, least able to manoeuvre and has least depth to hide in. Laying them means going deliberately into the most dangerous water available, at slow speed, holding a precise course, and staying there long enough to get the whole load away. Porpoise was lost doing this, twelve years and one world war after she was built for it. The next HMS Porpoise (S01), built in the 1950s, gave a later class its title, and HMS Cachalot carries the story of another of these minelayers, rammed by an Italian torpedo boat in 1941.

A War Fought Across Three Oceans

Porpoise operated in the North Sea in 1940, before serving in the Mediterranean from late 1941 through 1942, where she sank a number of merchant and military vessels in the kind of hard, sustained patrol work that defined the submarine war in that theatre.

The First Submarine Tanker

Her Mediterranean service included something no tally of sinkings captures, and it may be the thing she is most worth remembering for. In 1941 and 1942 Malta was being bombed into the ground and starved at the same time, and surface convoys were being destroyed trying to reach it: the convoys that saved Malta cost the Royal Navy a great deal, and even the successful ones arrived with a fraction of what had set out. What got through in between was carried by submarines, and Porpoise was the first of them fitted to do it properly. She has a fair claim to being the Royal Navy's first submarine tanker.

A minelayer was the obvious boat for it. The long external casing built to hold fifty mines could be adapted to hold something else, and what Malta needed was aviation spirit for the fighters defending it, ammunition, torpedoes for the submarines based there, and food. So the mine stowage was given over to fuel and stores, and boats like Porpoise made the run from Alexandria or Gibraltar submerged by day, on the surface by night, into an island under more or less continuous air attack.

It is worth being clear about what that meant for the men aboard. A submarine carrying petrol in her casing is carrying the one cargo she is least suited to: a fuel-air mixture is the standing nightmare of every submariner, the boat has no space to isolate it, and a depth charge close enough to spring a seam becomes something considerably worse than a depth charge. They did it anyway, repeatedly, and Malta held. The island held partly because of aircraft that flew on fuel delivered inside a submarine's minelaying casing.

By 1944 she had moved on again, this time to operate against Japanese forces in the Pacific, and on 11 September 1944 she took part in Operation Rimau, ferrying twenty-three British and Australian commandos as part of one of the most daring and ultimately tragic special operations of the entire Pacific war.

Rimau deserves the whole story. It was the sequel to Operation Jaywick, a raid the previous year in which a small party had paddled into Singapore harbour and sunk or damaged several ships with limpet mines, and got clean away. Jaywick had been an almost impossible success. Rimau was the attempt to repeat it on a larger scale, and it went wrong in almost every particular.

Porpoise carried the party from Western Australia on 11 September 1944 and put them ashore on Merapas Island, which was to be their base and the rendezvous for their extraction. They seized a local fishing boat, the Mustika, and intended to use her to get close to Keppel Harbour, from which the men would launch Sleeping Beauties, one-man motorised submersible canoes, to plant limpet mines on shipping. The attack was set for the night of 10 October.

It came apart before it began. A Japanese police patrol boat challenged the Mustika, one of the raiders opened fire, and the element the entire operation depended on was gone in a few seconds. Lyon scuttled the Mustika with all the equipment aboard and took a small party of six into the harbour anyway, where they destroyed three ships. Then the Japanese came after them, and there was nowhere in the Riau Archipelago for twenty-three men to go.

Thirteen were killed, Lyon among them, either fighting or trying to escape through hundreds of miles of Japanese-held islands. Ten were captured. Those ten were held, tried and beheaded at Singapore on 7 July 1945, five weeks before the Japanese surrender. The submarine sent to collect them from Merapas had already come and gone without finding anybody.

Lost With All Hands Off Penang

HMS Porpoise was sunk on 19 January 1945 by Japanese aircraft near Penang, with the loss of her entire crew of 59 men, the last Royal Navy submarine ever lost to enemy action. Japanese records describe a submarine spotted and bombed in the vicinity, damaged rather than destroyed, and leaking the oil that led their anti-submarine aircraft to her.

The end was slower than a single bomb. She had been laying mines off Penang, and the signal reporting that the lay had been completed successfully is the last anybody heard from her. The Japanese account has an aircraft finding a submarine in that area and bombing her without destroying her. What the attack did was damage her enough to start a leak of oil, and an oil trail on the surface is a line on a chart pointing at where a submarine is going. Their anti-submarine aircraft followed it, and it is likely she was sunk shortly afterwards.

Whether anybody aboard knew what was happening is unknowable. A submarine cannot see her own wake. She may have gone deep believing she had shaken off the aircraft, with a thin bright line following her across the Malacca Strait at four knots. Fifty-nine men, and no survivors and no wreck ever found.

She was the last Royal Navy submarine lost to enemy action, and she remains so. Nothing since January 1945 has been sunk by an enemy, through Korea, the Falklands and the whole of the Cold War, which is a remarkable thing to be able to say about eighty years of a service that has never stopped going to sea. HMS Thule and HMS Stygian were working the same water in the same months and both came home.

The arithmetic of her last year is worth sitting with. In September 1944 she carried twenty-three men to an island and left them there. In January 1945 she was killed off Penang with all hands. In July 1945 the last ten of the men she had landed were beheaded at Singapore. Of the fifty-nine men in the submarine and the twenty-three she landed, not one was alive when the war ended.

It was a devastating loss of experienced submariners who had already fought across three different theatres of war.